The overall objective of this series of experiments is to determine which phonosurgical method or combination of methods (ie vocal fold augmentation and laryngoplasty) is the most effective treatment of glottic incompetence. This will be approached by longitudinal clinical evaluation of human subjects, laboratory analysis of the impact of intracord injection and laryngoplasties in the excised larynx model and in vivo in the canine larynx model, and with long-term histological studies in the canine larynx. Evaluation will include use of standardized measures and development and application of a new technology, inverse filter technique. The studies address one of the NIDCD National Strategic Planning Committee's recommendation for major clinic research opportunities to expand use of phonosurgical methods through standardized measurements of vocal output before and after surgery, and of simulation modeling to predict vocal outcome before surgical manipulation. As such data gathered should be of significant value and interest to otolaryngologist, vocalogists, and speech scientists as well as to the patients who will benefit from improved treatment. The studies will be conducted in parallel, and in collaboration with other scientists within the Center in order to enhance our understanding of disordered voice production and its surgical remediation.